Staphylococcus aureus (“S. aureus” or “SA”) is a facultative anaerobic, Gram-positive bacterium, whose natural reservoir includes the human skin and nose and can also inhabit wounds. Most people who carry S. aureus show no sign of infection; however, S. aureus can become invasive and cause infection in the body if the normal barrier is breached. S. aureus can cause a number of illnesses ranging from minor skin infections such as pimples, boils, and abscesses, to major diseases such as pneumonia, meningitis, and sepsis. Tissues other than skin and nose can be infected when barriers are breached, e.g., skin or mucosal lining, which leads to furuncles and carbuncles. S. aureus infections can spread between people through skin contact with an infected person or contact with objects used by an infected person.
S. aureus posses a remarkable ability to develop resistance to the major antibiotics, including the penicillins (methicillin, oxacillin, cloxacillin and flucloxacillin), which has earned it the label “superbug”. Methicillin-resistant S. aureus (MRSA) is a bacterium that has become resistant to penicillins, and it is responsible for several human infections that are difficult to treat. MRSA may also be known as oxacillin-resistant S. aureus (ORSA) and multiple-resistant S. aureus, while the non-methicillin resistant strains of S. aureus are sometimes called methicillin-sensitive S. aureus (MSSA).
Diagnosis of S. aureus infection can include a physician evaluation of a patient's symptoms, which is normally not definitive because the infection may have been caused by another bacterium, such as Streptococcus pyogenes. Blood tests, urine analysis, and sometimes x-rays can be used to diagnose S. aureus infections. A definitive diagnosis may require a culture test, which can only be obtained after many hours or days, delaying the patient's treatment.
Certain PCR assays have been developed that are designed for the specific detection of MRSA due to its increased clinical significance in hospital and community acquired diseases. Literature indicates, however, that there is also significant clinical need to detect S. aureus whether or not it is antibiotic resistant.